Strong CP Problem and the Natural Hierarchy of Yukawa Couplings

A possible solution to the strong CP problem is presented without using an axion. The model is based on the framework of the supersymmetric vectorlike theory with the spontaneous breakdown of the P-C-T-invariance. It is shown that the characteristic structure of the Yukawa coupling matrices that results from the spontaneous P-C-T-breaking plays the essential role in naturally realizing $\theta=0$ at the tree level. It is argued that $\theta=0$ will not be affected by the radiative corrections.Comment: 31 pages, no figure

Charged lepton and down-type quark masses in SU(1,1) model and the structure of higgs sector

The simplest noncompact group SU(1,1),when introduced as a symmetry group of the generations of quarks and leptons in the framework of a vector-like theory, gives an excellent viewpoint on low energy physics. The minimal setup of the scheme, however, gives phenomenologically unacceptable prediction on the Yukawa coupling matrices. This suggests the higgs sector has richer structure than we expect from the success of MSSM. The natural extension of the scheme, which has doubled structure in the higgs sector, is formulated. The framework admits this extension in a restrictive way. The possible patterns of Yukawa couplings are classified and the expressions of the coupling matrices are presented.Comment: 25 pages, no figure